I have a number of mobile homes that are rental units in a very cold part of Arizona (due to be 2 degrees in the morning). I have replaced the furnaces in the past three years with new Intertherm gas furnaces. I now have three of the furnaces that go out in the middle of the night, in order to get them to come back on I have to flip the electric breaker, on one I can turn the thermostat to off wait a few minutes and then turn it back on and the unit will function. This is very upsetting to tenants and I fear frozen pipes, as it happens in the middle of the night and the tenant wakes when it get too cold. I have replaced the thermostats, and have had a repair man in to check them on several occasions, but he cannot find the problem. Any suggestions?

Are the furnaces on a circuit by themselves or is there other things on the same circuit?

Make sure the furnace ground (green or bare copper wire) from the electric panel to the furnace is continuous and grounded properly in all areas. The new furnaces that have a circuit board are very sensitive to bad grounds.

Mobile homes according to the National Electric code are supposed to be fed by a 4 wire system from the outside panel to the main inside electric panel with the neutrals and grounds separated and landed on different bars in the indoor electric panel. If that set up is not correct the neutral or furnace ground wire will pick up harmonics which will not allow the furnaces to operate properly.
This is very hard to explain in this type of venue so I suggest you contact a electrician in your area who is AWARE of proper wiring for mobile homes. I cannot count how many of these mobile homes around here I have repaired the power on after a new style furnace has been installed.
Good Luck.